By Isabelle Hall
Traditional healing methods have been practised by Aboriginal groups in Australia for over 60 000 years. Among indigenous communities, the use of specific medical treatments varies according to location and cultural convention. In the state of Victoria, Gukwonderuk (Centipeda cunninghamii, also known as Old Man’s Weed) has been used by the Wotjobaluk people to treat arthritis and joint pain. Extracts from this herb are also present in manufactured remedies targeting issues such as skin inflammation (Healy, 2018). Gukwonderuk is a source of thymol, an antibiotic and antifungal compound which appears to act via multiple pathways, including on the mechanisms in which membrane integrity is altered(Marchese et al., 2016). Another common plant remedy from south eastern Australia involves the sap of Cherry Ballart (Exocarpos cupressiformis – Native Cherry), which can be applied to snakebites.
Victorian Aboriginal groups have also utilised Kangaroo Apple (Solanum aviculare, or Solanum laciniatum) as a source of medicine. This nightshade plant is known for its lobed leaves, which bear a similarity to a kangaroo’s paw, and its production of a fruit which is poisonous prior to ripening. Glycoalkaloids (such as solanine, present in Kangaroo Apple) found in plants of the genus Solanum can cause harm via inhibition of cholinesterases, including acetylcholinesterase (McGehee, 2000). Such activity prevents enzyme-catalysed breakdown of the neurotransmitter acetylcholine, thus increasing its levels and raising the risk of overstimulation within the nervous system. While application of Kangaroo Apple as a remedy carries this risk, significant medicinal benefits may be also gained from it.
One advantage of its use relates to the steroidal alkaloid solasodine, which can be obtained from its leaves and young fruit (Healy, 2018). Previous research has indicated that Solanum glycosides, such as solasodine, may exhibit hormonal activity in vitro – one way this may occur is via binding to oestrogen receptors (Jisha et al., 2011). The presence of a compound with this property in Kangaroo Apple is integral to its use as a female contraceptive. To avoid pregnancy, women may consume a tea made by boiling the unripe fruit (Critchley, 2018). Upon use of this treatment, any oestrogenic behaviour displayed by solasodine may then lead to decreased secretion of the follicle-stimulating hormone (FSH). As a result, follicle development will be inhibited and ovulation should not occur.
Kangaroo Apple has also been cultivated in Russia to provide a source of solasodine, which can then be converted to steroid hormones such as progesterone (Healy, 2018). Progesterone, much like solasodine, also has contraceptive capabilities, and is widely used in the manufacture of commercial contraceptives; Progesterone suppresses ovulation, by preventing surges of follicle-stimulating hormone and luteinising hormone. Its contraceptive effect is also linked to its ability to thicken cervical mucus and create an endometrium which is not suitable for implantation of a fertilised ovum.
Aside from its hormonal activity, solasodine appears to display pharmacological effects, including antifungal and anticancer behaviour (Patel et al., 2013). As a source of solasodine and other alkaloids, Kangaroo Apple has proven useful in traditional bush medicine as well as in manufacturing procedures, such as those used to produce contraceptive pills. Greater exploration of Kangaroo Apple as a medical treatment may be undertaken, given the array of potentially useful effects attributed to the alkaloids it contains.
The successful use of treatments such as Kangaroo Apple and Gukwonderuk in Aboriginal bush medicine demonstrates the need for further study into traditional healing methods employed by Indigenous Australians, as well as by other indigenous groups around the world. Through gaining insight into traditional medicinal knowledge and customs, Western science may incorporate other effective practices, or adapt them for targeted use. Implementing a more diverse array of medical treatments may assist us in addressing urgent threats such as the rise of antibiotic resistance.
Critchley, C. (2018) The endurance of bush medicine. Available from: https://pursuit.unimelb.edu.au/articles/the-endurance-of-bush-medicine [Accessed 30th September 2020]
Healy, J. (2018) The art of healing: Australian Indigenous bush medicine. Melbourne, Medical History Museum, University of Melbourne.
Jisha, S., Sreeja, S. and Manjula, S. (2011). In vitro & in vivo estrogenic activity of glycoside fractions of Solanum nigrum fruit. The Indian Journal of Medical Research. 134(3), 369-374. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3193719/ [Accessed 30th September 2020]
Marchese, A., Orhan, I.E., Daglia, M., Barbieri, R., Di Lorenzo, A., Nabavi, S.F., Gortzi, O., Izadi, M. and Nabavi, S.M. (2016) Antibacterial and antifungal activities of thymol: A brief review of the literature. Food chemistry. 210, 402-414. Available from: doi: 10.1016/j.foodchem.2016.04.111
McGehee, D.S., Krasowski, M.D., Fung, D.L., Wilson, B., Gronert, G.A. and Moss, J. (2000) Cholinesterase inhibition by potato glycoalkaloids slows mivacurium metabolism. Anesthesiology: The Journal of the American Society of Anesthesiologists. 93(2), 510-519. Available from: doi: 10.1097/00000542-200008000-00031
Patel, K., Singh, R.B. and Patel, D.K. (2013). Medicinal significance, pharmacological activities, and analytical aspects of solasodine: A concise report of current scientific literature. Journal of Acute Disease, 2(2), 92-98. Available from: doi: 10.1016/S2221-6189(13)60141-9